This invention relates to a helical-scan information recording-playback apparatus, and particularly to an information recording-playback apparatus having a function of pre-recording a control signal or time code signal on a certain track in the longitudinal direction of the tape.
Video tape recorders (VTRs) based on the digital signal processing are superior to conventional VTRs based on the analog signal processing in the picture quality, dubbing function and usage. On this account, VTRs, particularly business-oriented VTRs, are now in the transition to digital models. The digital VTRs are standardized, for example, as the D-2 format composite digital VTR described in Proposed American National Standard, V16.83, Apr. 1, 1988, pp. 1-10; V16.87-441Apr. 1, 1988, pp. 1-40; and V16.88-422, Apr. 1, 1988, pp. 1-3.
The digital VTRs are designed to pre-record the time code and control signal on a longitudinal track of the tape, and have the pre-formatting function for the tape evaluation or assessment, with the intention of enhanced usage at editing.
The following explains the pre-formatting with reference to FIGS. 1 and 2. FIG. 1 shows the arrangement of rotary heads for helical scanning, in which indicated by 2 is a cylinder, 2a and 2b are recording heads, and 2c and 2d are playback heads. FIG. 2 shows a tape pattern created by pre-formatting a magnetic tape, in which indicated by 1 is a magnetic tape, 2a and 2b are recording magnetic heads, 2c and 2d are playback magnetic heads, 3 and 3T are a control signal head and a control signal track, respectively, and 4 and 4T are a time code head and a time code track, respectively.
Pre-formatting is to record the passing of time since the tape head in "hour", "minutes" and "seconds" and a video frame number ranging from 0 to 29 on the time code track 4T, and to record a reference signal for the rotational phase of the capstan, i.e., a control signal which provides the reference for tracking control. The recorded time code facilitates editing such as "insert". For tape evaluation, some video signal, e.g., black burst signal, converted into a digital signal is recorded with the rotary heads 2a and 2b, separately from the time code and control signal, so that it is subsequently reproduced with the playback heads 2c and 2d shown in FIG. 1 thereby to detect errors in the reproduced digital signal, with the intention of warning the user of the use of the tape having much errors that are hindrance to have satisfactory picture and sound qualities, with a view to enhance the recording reliability.